Lightmap Seams

Inspect Lightmap Seams checks the baked lightmaps along the joins between neighbouring faces and lists the joins where the two sides are lit differently. Blend Selected Faces evens out the baked lighting across the joins between faces you pick. Both work on the lightmaps you already have: neither traces any light.

Where to find it

All three commands are only in the RED+ menu:

• RED+›, Inspect Lightmap Seams (RF+) opens the Lightmap Seam Inspector window.
• RED+›, Blend Selected Faces (RF+) blends the joins between the selected faces.
• RED+›, Undo Last Blend (RF+) restores the last blend.

Inspect Lightmap Seams

1. Calculate lighting, or open a map that already has baked lighting.
2. Choose Inspect Lightmap Seams (RF+). The window opens and scans the level straight away.
3. Select a row. Its join turns cyan in the Free Look view.
4. Click Go To, or double-click the row. All four views move to the point where the difference is largest. The Free Look view keeps its direction and stands back from that point.
5. Fix the cause and calculate lighting again, or blend the join (below).

The window stays open while you work in the editor, and choosing the command again brings it to the front. While it is open, the list refreshes by itself after each bake.

Reading the list

The status line gives the number of suspect joins, the number of joins checked, and how many edges were left out as unmatched or ambiguous.

Each row describes one join:

• Flat join or Shallow bend. In the Free Look view, flat joins are drawn red and shallow bends orange.
• difference: the largest lighting difference found along the join, on a 0 to 255 scale per colour channel.
• faces: the face ID on each side.
• surfaces: the lightmap surface ID on each side.
• density: the higher lightmap density of the two sides divided by the lower one. A high value points to a sharp side meeting a blurry one. See Show Lightmap Density.
• bend: the angle between the two faces, in degrees.

The joins with the largest difference come first. The same face ID can appear on both sides of a join.

What it measures

A join is an edge shared by exactly two faces that are on different lightmap surfaces, lie on opposite sides of the edge, and meet at an angle of about 1 degree or less. A join is flat when both faces lie in the same plane. Any other join is a shallow bend.

Along each join, the inspector compares the two sides at 129 points, leaving out the first and last 3 % of the edge. Each side is sampled from its own lightmap with bilinear filtering. A join is listed when the two sides differ by more than 8 on any colour channel.

Edges are matched by their end points, rounded to 0.0001 units. Edges whose ends miss by more than that count as unmatched, not as seams.

A result is a lead, not proof of a fault. A bend can change brightness naturally, and a flat join can have different shading normals or material settings on each side.

What it leaves out

• Sky faces, liquid surfaces, invisible faces, portals, and faces set to Full Bright, Full Dark or Emissive Light.
• Faces without a baked lightmap.
• Edges used by only one face, which includes T-junctions, and edges used by three faces or more.
• Joins that bend by more than about 1 degree.
• Movers and meshes. Only the compiled static world is checked.
• Shadow shapes and stair-stepping inside a face. An empty list does not mean the lighting is free of other artefacts.

Blend a join from the list

Blend Selected in the window adjusts the lightmap texels right next to the selected join, on both sides, so that the two sides match more closely along the edge. It changes nothing else. A join can stay in the list after a blend.

• It is available while the results are current and a row is selected.
• When it has blended, the window scans again and the status line says how many texels changed.
• Undo Blend restores the texels that the last blend changed.
• A shallow bend can contain natural shading. Blend it only when the difference is a seam.

Blend Selected Faces

Use this to even out joins the list does not show, or to pick the joins yourself.

1. Select two or more faces that share edges (Face mode or Texture mode).
2. Choose RED+›, Blend Selected Faces (RF+).

RED+ blends every join between the selected faces, whatever the difference, and says how many joins it blended and how many texels changed. A join qualifies when its two faces are on different lightmap surfaces and lie in one plane or meet at a bend of 30 degrees or less. Full Dark, emissive, sky, liquid, Full Bright and invisible faces are left out, and the map must have been lit since its geometry was last built. If the selected faces share no join that qualifies, RED+ says so and changes nothing.

Keeping a blend

• RED+ marks the level as changed. Save the map to keep the blend.
• RED+›, Undo Last Blend (RF+) and Undo Blend in the window both restore the last blend, from either command. Only the last blend can be undone.
• Undo is possible until you calculate lighting, apply Face Properties or change the geometry.
• Calculate Lighting replaces all blends.

Keeping results current

The results go out of date when a bake starts, when you apply Face Properties, and while the geometry needs a rebuild. The status line then says Results are out of date. Recalculate lighting if needed, then Scan. Click Scan to check again. After opening another level, click Scan before you use the list.

If you click Scan while the geometry needs a rebuild, the status says Rebuild geometry and calculate lighting first.

The joins are drawn only in the Free Look view, and only while the window is open and its results are current.

Limits

If the level has more than 50,000 faces, or more edges than the inspector can check, the scan stops and says so. It never shows a partial list.